Firewall has nothing to do with access to your contacts. The Privacy section in System Preferences is responsible for this. The first time a program tries to access your contacts, the operating system asks you for permission. Later you can allow or disallow in the Privacy section.

Please do this:1. Create a new blank document.2. Select Insert > Address Field > Full Name in the main menu.3. Click on the Print button in the toolbar.4. Click on the Print List button.What happens in response?Can you see the list of contacts?